(1) Field of the Invention
The present invention relates to a supervisory system in a communication system wherein a plurality of unattended repeater stations and attended terminal stations, each of which is ranked as a central master station, a master station, and a slave station, are connected in a tandem arrangement. The stations are connected with a logical hierarchical configuration for processing supervisory information, and the supervisory information of the slave stations is easily collected.
(2) Description of the Related Art
In a communication system such as a telephone exchange network, a data transmission system is known wherein terminal stations located in urban areas are interconnected through a plurality of unattended repeater stations by, for example, optical cables or the like, so as to form a tandem link, and audio data is transmitted at a speed as high as 400 Mb/s. In such a system, the distance between the repeater stations is several tens of kilometers, supervisory information or the like at each repeater station is collected at the terminal stations or supervisory information or the like at each of the repeater stations and the terminal stations is collected at a central station, the information collected at the terminal stations or the central station is analyzed, a faulty portion thereof is distinguished, maintenance is carried out and the system is restored.
In the above-mentioned data transmission system, lines for collecting information are installed between each repeater station and a terminal station or between each repeater station and a central station, and remote supervision is performed by collecting supervisory information at the repeater stations or the terminal stations at the terminal station or the central station, respectively. However, since special lines for collecting the information, other than the data transmission lines, must be laid, the disadvantage of higher line costs is incurred.
Another disadvantage is when the supervisory information or the like is collected at the central station through the line for collecting the information and through the terminal station, if a fault occurs at the terminal station, the supervisory information from the repeater station collected at the terminal station cannot be collected.
The present invention is proposed to alleviate the above-mentioned conventional disadvantages.